When Sen. Dick Durbin took over the powerful defense subcommittee of the Senate Appropriations Committee in late January, the Illinois Democrat knew that he had some work to do.

Durbin, No. 2 in the Senate Democratic leadership and a 26-year member of both the House and Senate Appropriations panels, has spent the past three months in a crash course on defense issues, poring over briefing books, meeting with Pentagon officials and defense experts, and touring military bases.

“I’m a nontraditional appointment to the committee because the three [chairmen] before me had extensive backgrounds working in armed services and certainly serving in the military. I don’t have that,” Durbin said in a huge understatement. “So I come to this with a lot of humility. I have a lot to learn, and I’m doing my best to learn it as fast as I can.”

When he refers to the previous chairmen, Durbin is speaking of the late Sens. Daniel Inouye (D-Hawaii) and Ted Stevens (R-Alaska), who kept iron-fisted control of the defense subcommittee gavel all the way back to 1980.

Inouye lost his right arm fighting the Germans in World War II and was later awarded the Medal of Honor for his bravery. Stevens flew C-47 cargo planes over “the Hump” — the Himalayas — to help resupply Chiang Kai-shek’s Nationalist forces as they fought to liberate China from Japanese invaders. Stevens received two Distinguished Flying Crosses for his efforts, as well as other military decorations.

“Ever since I’ve been here, Stevens and Inouye have run the committee,” said Senate Majority Leader Harry Reid (D-Nev.), who came to the Senate in 1986. Reid then joked that “maybe [Durbin] is a defense hawk.”

Prior to the Stevens-Inouye era, the post was held by Sen. John Stennis (D-Miss.), often referred to as the “Father of the Modern Navy.” Stennis chaired both the Appropriations and Armed Services committees during his 42 years in the Senate, and the aircraft carrier USS John Stennis was named after him.

In fact, just seven different senators have chaired the defense appropriations subcommittee during the past 80 years, according to Senate records.

And now there’s Durbin, with his law degree from Georgetown University and impeccable progressive credentials, helping to oversee the budgets of the Pentagon, the CIA and other national security agencies. Other Democratic senators and aides already chuckle about seeing Durbin “surrounded by admirals and generals all the time,” people who must now seek his support for their own military priorities.

It’s also the same Durbin who voted against the 1991 Persian Gulf War; who opposed the 2003 U.S. invasion of Iraq; who compared — to his later regret — U.S. interrogators at Guantánamo Bay to “Nazis, Soviets in their gulags or some mad regime — Pol Pot or others — that had no concern for human beings”; who has been openly critical of President Barack Obama’s use of unmanned drone aircraft to attack suspected terrorists overseas; and who is now involved in bipartisan talks to revise the congressional resolution authorizing the use of military force against Al Qaeda following the Sept. 11, 2001, terrorist attacks.

Durbin’s appointment to the sensitive post, though, has pleased many of his more liberal Democratic colleagues — and some Republicans — who grumbled quietly for years that Inouye and Stevens “rubber-stamped” the Pentagon budget while seeking hundreds of millions of dollars in spending earmarks for their home states.

“It’s big, big, big,” said Sen. Tom Harkin (D-Iowa), also a member of the defense subcommittee. “It really is about time that we got someone who is willing to take a real independent, nonbiased view — one way or the other — on defense spending.”

“I’ve known Dick Durbin since we both came to the House in 1982,” said Sen. John McCain (R-Ariz.), a senior member of the Armed Services Committee. “I view him as very centrist. I’ve never known him to be ‘anti-defense.’ He’s a thoughtful guy. He’s also in the leadership of the Democrats, so he then has even more influence.”

Durbin is cautious in what he hopes to accomplish with his new chairmanship. Like other lawmakers, Durbin wants to reform the way the Pentagon buys big-ticket weapons systems. And like Appropriations Committee Chairwoman Barbara Mikulski (D-Md.) and the White House, Durbin is extremely concerned about the fallout of sequestration cuts on the Pentagon.

Air Force officials announced on Tuesday that budget cuts have forced them to temporarily ground as much as one-third of the U.S. combat aircraft.

Across the entire Defense Department, the “vast majority” of its 880,000 civilian employees are facing as many as 14 furlough days before the end of the fiscal year on Sept. 30. Future annual budgets may see even more dramatic cuts as Obama and lawmakers in both parties seek to further reduce the federal deficit.

“My view on this budget will be different than my predecessors, and I’m sure that each of them could have said the same thing,” Durbin said in an interview. “But I will tell you this — I am walking to a daunting thing, the largest single appropriations subcommittee, which has all of the spending for both the military and intelligence. That’s a big thing.”

Durbin added: “What I am trying to do is to measure the need to cut spending with the absolute requirement that we not compromise our national defense. It is challenging. It would be challenging for anyone.”

In particular, Durbin has serious concerns about the troubled F-35 Joint Strike Fighter, already on track to be the most expensive weapons program in U.S. history. Some analysts expect the program to cost as much as $1 trillion.

“It appears, that at least for some time now, Congress has shrugged its shoulders and said ‘You can’t quit on it. No matter how bad it goes, you can’t quit on it,’” Durbin said. “I’m new, and I’m going to ask some questions about that conclusion, and whether or not there are ways to deal with it that will make us safer and not cost us so much money.”

He added, “The F-35 Joint Strike Fighter is the premier argument for revisiting our acquisition policy. We’re deep in the sauce when it comes to some of these projects and whether they will ever meet the defense needs of our nations.”

Durbin noted that big defense contractors are shrewd in doling out portions of weapons programs to different states and regions, looking for support on the Hill when they run into political trouble.

“They understand the politics,” he said. “In a recovering economy with a desperate need for jobs, that becomes a political force in the argument.”

Durbin traveled to Miami last week to get a briefing from military officials on the detention facility in Guantánamo, a hugely important issue for both the White House and Congress.

“We have 166 detainees. The annual appropriations for Guantánamo is around $250 million. That means our net cost per detainee is $1.5 million annually,” Durbin said. “We now have human-rights issues, as a number of detainees are now starving themselves. We have a number of these detainees who we have concluded are no threat to the United States, but no one will take them.”

Durbin promised a hearing on the issue but will not try to add language to the Pentagon bill shutting down the facility. “I want to come up with something that has bipartisan support,” Durbin said.